Bremsstrahlung Effect at Resonant Compton Scattering of a Photon by a Multielectron Atom

JETP Letters - The leading role of the bremsstrahlung at resonant Compton scattering of a hard X-ray photon by a multielectron atom has been theoretically predicted. This result can be important in...     

Effect of Quadrupole Emission in Scattering of Two Photons by an Atom

JETP Letters - A pronounced quadrupole emission effect is theoretically predicted in terms of the contact interaction operator in resonant inelastic scattering of two X-ray photons near the...     

Bremsstrahlung in Resonant Compton Scattering of a Photon by an Atom

Journal of Experimental and Theoretical Physics - An analytic equation for the anomalous magnetic moment of an electron in a static magnetic field in the topologically massive 2D electrodynamics is...     

Merging of X-Ray photons in the field of a light atomic ion

The process of merging of three X-ray photons into one photon in the field of a light atomic ion is theoretically studied. A pronounced resonance structure and a strong angular anisotropy of the differential cross section for merging are predicted in the region of the incident photon energy ?ω ? I _1s /2 (I _1s is the threshold energy of ionization of the -shell of the ion). The magnitude of the observed merging cross section is estimated.     

Elastic Scattering of Two Photons by a Multicharged Atomic Ion

The elastic scattering of two X-ray photons by a multicharged atomic ion has been studied theoretically. A pronounced resonance structure and strong angular anisotropy of differential scattering cross section have been predicted in the energy range of a scattered photon from ?ω–I_1s to ?ω+I_1s (where is the energy of the incident photon and is the ionization energy threshold of the shell of the ion). The absolute value of the observed cross section has been quantitatively estimated.     

Merging of photons in the field of a multielectron atom: Higher orders of perturbation theory

The contribution of higher orders of relativistic quantum perturbation theory to the differential cross section for the merging of three X-ray photons into one photon in the field of a multielectron atom has been studied in the Tamm–Dankov approximation. It has been shown that higher orders do not change the physical results obtained in the leading (second) order of perturbation theory.     

Resonant inelastic scattering of an X-ray photon by a linear molecule

The double differential cross section of resonant inelastic scattering of a linearly polarized X-ray photon by a spatially oriented HF molecule in a gas phase is theoretically described in the energy range of the ionization threshold of the deep molecular orbital 1σ. The effects of radial relaxation of the wave functions of the core and excited scattering states in fields of the formed core vacancies, the vibronic effects, and the effects of Auger and radiative decays of the vacancies are taken into account in the nonrelativistic Hartree-Fock approximation. The results of the calculations are predictive and agree well with the results of the experimental measurements of the Kα emission spectrum of the HF molecule at an incident photon energy of 2 keV, which considerably exceeds the energy of the 1σ ionization threshold.     

Resonant inelastic contact scattering of X-ray photons on atoms and ions

The existence of an extended resonance structure outside the X-ray emission regions is theoretically predicted in the total double differential cross section for the scattering of linearly polarized photons on free atoms (ions). This structure is almost entirely determined by inelastic photon scattering of the contact type. The amplitude of the inelastic contact scattering probability is described using an analytical expression for a non-relativistic transition operator, which was previously obtained by the author outside the dipole and momentum approximations. The resonant inelastic contact scattering of X-ray photons on a neon atom and neonlike ions of argon, titanium, and iron has been studied. Calculations were performed in a nonrelativistic approximation for the wave functions of the scattering states, with allowance for many-body effects of the radial relaxation of one-electron orbitals in the Hartree-Fock field of a deep 1s vacancy and (for neon atom) the double excitation/ionization of the ground atomic state.     

Resonant Compton Scattering of Two Photons by a Multiply Charged Atomic Ion

JETP Letters - A pronounced K α1,2 X-ray emission spectrum is theoretically predicted for the resonant inelastic scattering of two photons in the energy region near the 1s shell ionization...     

Inelastic scattering of an X-ray photon by a manganese atom

The influence of multiplet and many-particle effects on the shape and magnitude of the double differential cross section of resonant inelastic scattering of a linearly polarized X-ray photon by a free atom with an open shell in the ground state within the energy range of the K ionization threshold is theoretically investigated using a manganese atom as an example. The radial relaxation of electron shells, spin-orbit and multiplet splittings, configuration mixing in intermediate scattering states, and Auger and radiative decays of newly formed vacancies are taken into account. The results of the calculation are predictive.